Education

Areas of Specialization/Research

As a plant pathologist with the Louisiana State University Agricultural Center, my
main job responsibility is the development of a research program addressing diseases
caused by viruses in Louisiana crops. Other duties include teaching a graduate course
and a laboratory on plant virology, directing graduate student research, and working
with extension personnel on the diagnosis of viral diseases.

Based on the type of relationship with the host, plant viruses can be grouped as acute
or persistent. Most acute viruses cause disease and have been well studied. Due to
the apparent lack of effect on the host phenotype, limited information is available
on persistent plant viruses. Persistent plant viruses are dsRNA virus members of the
families Endornaviridae, Chrysoviridae, Partitiviridae, and Totiviridae. They have
been reported to infect several economically important crops, such as avocado, alfalfa,
barley, beets, cherry, common bean, fava bean, melon, pepper, rice, and tomato, among
others. My laboratory and collaborators have identified persistent virus-free and
persistent virus-infected lines of cultivars of bell pepper, common bean, and jalapeño
pepper. Preliminary comparative experiments using these lines suggest that in some
cases, these viruses may have an effect on the phenotype, seed/fruit yield, seed emergence,
and the host reaction to some acute plant viruses. It is possible that the persistent
viruses are in a symbiotic (mutualistic) relationship with the host and provide an
unknown benefit.

Virus identification is important for developing control strategies, and another area
of my research program focuses on plant virus identification and characterization
and the development of detection tools. Graduate students in my laboratory and collaborators
have identified, characterized, and developed detection tools for several newly recognized
virus species causing diseases on sweet potato, pepper, tomatoes, citrus, common bean,
and ornamental crops.

Valverde, R. A., and Dodds, J. A. 1986. Evidence for a satellite RNA associated naturally
with the U5 strain and experimentally with the U1 strain of tobacco mosaic virus.
Journal of General Virology 67:1875-1884.